In the molding of reinforced plastic parts, fabric insert is frequently used to improve the strength and the modules of a molded part. Molded reinforced plastic parts have been used in the automotive industry where automobile body members are designed and manufactured by such techniques. For instance, in an automobile body member that requires high stiffness, high modules and controlled dimensional stability, a reinforcing fabric is frequently placed in a mold cavity to be encapsulated by a molding resin. Fabrics of either woven or non-woven construction can be used in such reinforcing applications. Reinforcing mats formed of various fibers can also be used.
Reinforcing filamentary yarns are often used in weaving a fabric for molding a fabric reinforced polymeric composite part. The fabric is constructed as an ordinary biaxially woven fabric where the size and density of the warp and the weft are both the same in both directions and the warp and the weft crossing each other at right angle.
Reinforcing filamentary yarns of either organic or inorganic nature have been used in reinforced polymeric composite parts. The reinforcements are usually light weight as well as superior in tensile, compression and flexural properties. A polymeric composite part reinforced by such fabrics has been used as a structural member in place of a conventional metal part in various applications. For instance, a polymeric composite part reinforced with fabrics of carbon fibers has excellent light-weight property in addition to other desirable mechanical properties. Carbon fibers have been widely used as the structural reinforcement in the aircraft and aerospace industries for these reasons.
However, a drawback of using carbon fibers as the reinforcement in a plastic part is the fact that carbon fibers render the plastic brittle upon impact and produces a catastrophic failure mode where pieces are shattered upon breakage. This type of failure mode would not be permitted in the application of an automobile body part.
It is therefore an object of the present invention to provide an improved reinforcing fabric that does not have the shortcomings of the prior art fabrics.
It is another object of the present invention to provide an improved reinforcing fabric that is woven by an organic fiber yarn and at least one inorganic fiber yarn such that the fabric has superior impact, tensile, compression and flexural properties.
It is a further object of the present invention to provide an improved reinforcing fabric that is woven by a polyaramid fiber yarn and at least one inorganic fiber yarn such as glass or carbon to achieve a fabric that has superior physical properties.
It is yet another object of the present invention to provide an improved reinforcing fabric that is woven in both the warp and the weft directions by alternating polyaramid, carbon and glass fiber yarns to achieve a fabric having superior reinforcing properties.
It is still another object of the present invention to provide an improved reinforcing fabric that is woven of alternating polyaramid, glass and carbon fibers in both the warp and the weft directions such that an isotropic composite part can be produced.